RT Book, Section A1 Middeldorp, Saskia A1 Coppens, Michiel A2 Kaushansky, Kenneth A2 Prchal, Josef T. A2 Burns, Linda J. A2 Lichtman, Marshall A. A2 Levi, Marcel A2 Linch, David C. SR Print(0) ID 1178756198 T1 Hereditary Thrombophilia T2 Williams Hematology, 10e YR 2021 FD 2021 PB McGraw-Hill Education PP New York, NY SN 9781260464122 LK hemonc.mhmedical.com/content.aspx?aid=1178756198 RD 2024/04/18 AB SUMMARYThrombophilia refers to abnormalities in coagulation or natural anticoagulant molecules that increase the risk of venous thromboembolism (VTE). Over the past several decades, numerous factors have been identified. The most prevalent examples of hereditary forms of thrombophilia include the factor V Leiden and prothrombin G20210A mutations; deficiencies of the natural anticoagulants antithrombin, protein C, and protein S; persistently elevated levels of coagulation factor VIII; and mild hyperhomocysteinemia. Taken together, some form of hereditary thrombophilia can be identified in more than 50% of patients with VTE who are without obvious reasons for VTE, such as trauma or prolonged stasis. Moreover, hereditary thrombophilia has been associated with arterial cardiovascular disease and obstetric complications such as (recurrent) pregnancy loss and preeclampsia. The high yield of thrombophilia testing has led to widespread testing for these abnormalities in patients. Nevertheless, thrombophilia testing remains a topic of debate, mostly because of the lack of therapeutic consequences. Although hereditary thrombophilia is a clear risk factor for a first VTE, the risk for recurrent episodes is not significantly increased compared with nonaffected persons, and prolonged anticoagulation is not warranted unless VTE is recurrent. A similar lack of therapeutic benefit applies to patients with arterial cardiovascular disease and women with obstetric complications. Thrombophilia testing in asymptomatic relatives of patients with VTE may be useful in families with antithrombin, protein C, or protein S deficiency or for siblings of patients who are homozygous for factor V Leiden and is limited to women who intend to become pregnant or who would like to use oral contraceptives. Careful counseling with knowledge of absolute risks helps patients to making an informed decision in which their own preferences can be taken into account.